Fix build with latest gym (#1034)

* update to use latest version of gym

* fix imports

* narrow down gym version to 0.15.4 <= gym < 0.16.0

baselines/common/cmd_util.py

@@ -9,7 +9,7 @@ except ImportError:
     MPI = None
 
 import gym
-from gym.wrappers import FlattenDictWrapper
+from gym.wrappers import FlattenObservation, FilterObservation
 from baselines import logger
 from baselines.bench import Monitor
 from baselines.common import set_global_seeds
@@ -81,8 +81,7 @@ def make_env(env_id, env_type, mpi_rank=0, subrank=0, seed=None, reward_scale=1.
         env = gym.make(env_id, **env_kwargs)
 
     if flatten_dict_observations and isinstance(env.observation_space, gym.spaces.Dict):
-        keys = env.observation_space.spaces.keys()
+        env = FlattenObservation(env)
-        env = gym.wrappers.FlattenDictWrapper(env, dict_keys=list(keys))
 
     env.seed(seed + subrank if seed is not None else None)
     env = Monitor(env,
@@ -128,7 +127,7 @@ def make_robotics_env(env_id, seed, rank=0):
     """
     set_global_seeds(seed)
     env = gym.make(env_id)
-    env = FlattenDictWrapper(env, ['observation', 'desired_goal'])
+    env = FlattenObservation(FilterObservation(env, ['observation', 'desired_goal']))
     env = Monitor(
         env, logger.get_dir() and os.path.join(logger.get_dir(), str(rank)),
         info_keywords=('is_success',))

setup.py

@@ -31,7 +31,7 @@ setup(name='baselines',
       packages=[package for package in find_packages()
                 if package.startswith('baselines')],
       install_requires=[
-          'gym>=0.10.0, <1.0.0',
+          'gym>=0.15.4, <0.16.0',
           'scipy',
           'tqdm',
           'joblib',